Scalloping minimization in deep Si etching on Unaxis DSE tools

Shouliang Lai; Dave J. Johnson; Russ J. Westerman; John J. Nolan; David Purser; Mike Devre

doi:10.1117/12.472750

15 January 2003 Scalloping minimization in deep Si etching on Unaxis DSE tools

Shouliang Lai, Dave J. Johnson, Russ J. Westerman, John J. Nolan, David Purser, Mike Devre

Proceedings Volume 4979, Micromachining and Microfabrication Process Technology VIII; (2003) https://doi.org/10.1117/12.472750
Event: Micromachining and Microfabrication, 2003, San Jose, CA, United States

Abstract

Sidewall smoothness is often a critical requirement for many MEMS devices, such as microfludic devices, chemical, biological and optical transducers, while fast silicon etch rate is another. For such applications, the time division multiplex (TDM) etch processes, so-called "Bosch" processes are widely employed. However, in the conventional TDM processes, rough sidewalls result due to scallop formation. To date, the amplitude of the scalloping has been directly linked to the silicon etch rate. At Unaxis USA Inc., we have developed a proprietary fast gas switching technique that is effective for scalloping minimization in deep silicon etching processes. In this technique, process cycle times can be reduced from several seconds to as little as a fraction of second. Scallop amplitudes can be reduced with shorter process cycles. More importantly, as the scallop amplitude is progressively reduced, the silicon etch rate can be maintained relatively constant at high values. An optimized experiment has shown that at etch rate in excess of 7 μm/min, scallops with length of 116 nm and depth of 35 nm were obtained. The fast gas switching approach offers an ideal manufacturing solution for MEMS applications where extremely smooth sidewall and fast etch rate are crucial.

Citation Download Citation

Shouliang Lai, Dave J. Johnson, Russ J. Westerman, John J. Nolan, David Purser, and Mike Devre "Scalloping minimization in deep Si etching on Unaxis DSE tools", Proc. SPIE 4979, Micromachining and Microfabrication Process Technology VIII, (15 January 2003); https://doi.org/10.1117/12.472750

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